CS and C–S vibrations
The C2–S6 vibrations were observed with coupled vibrations of neighboring atoms. The strong C–S stretching vibrations are observed at 949 and 648 cm−1 in B3LYP and these Perifosine vibration modes are coincide with FT-IR band at 634 cm−1 (mode No’s: 33 and 38). The phenyl ring deformation vibration is observed very strongly at 810 cm−1 in FT-IR spectrum and its corresponding theoretical wavenumber assigned at 808 cm−1 from B3LYP. The rhodanine breathing mode is secondary (lateral) meristems strongly observed at 524 cm−1 in FT-IR and as medium band at 521 cm−1 in FT-Raman, the theoretical wavenumber well coincides at 524 cm−1 from B3LYP. The C–S vibrations accompanied with phenyl ring deformation and breathing mode vibrations of rhodanine. The in-plane bending and out-of-plane bending vibrations of C–S group were also found well within the characteristic region  and .